Back to EveryPatent.com
United States Patent | 5,614,890 |
Fox | March 25, 1997 |
A personal identification system includes a number of antenna preamplifier nodes coupled to collection nodes which are in turn coupled to a central computer. A personal detector unit attached to a user is inserted into an enclosure of the antenna preamplifier node. The antenna preamplifier node is electrically isolated by RF attenuation material. An antenna of the antenna preamplifier node is a low gain antenna. The antenna preamplifier node reads a coded radio frequency signal of a personal detector unit inserted into an enclosure and rejects signals of other various personal detector units in the vicinity.
Inventors: | Fox; Thomas M. (Gilbert, AZ) |
Assignee: | Motorola, Inc. (Schaumburg, IL) |
Appl. No.: | 173033 |
Filed: | December 27, 1993 |
Current U.S. Class: | 340/5.81; 119/51.02; 340/572.7; 343/703 |
Intern'l Class: | H04Q 001/00 |
Field of Search: | 340/825.31,825.34,825.69,825.72,825.54,572,573 343/703,841 119/51.02 |
3541995 | Nov., 1970 | Fathauer | 119/51. |
3898984 | Aug., 1975 | Mandel et al. | 128/2. |
4171684 | Oct., 1979 | Herr | 119/51. |
4259665 | Mar., 1981 | Manning | 340/575. |
4342986 | Aug., 1982 | Buskirk et al. | 340/539. |
4559526 | Dec., 1985 | Tani et al. | 340/539. |
4598275 | Jul., 1986 | Ross et al. | 340/573. |
4622544 | Nov., 1986 | Bially et al. | 340/636. |
4665387 | May., 1987 | Cooper et al. | 340/572. |
4672155 | Jun., 1987 | Naruse | 178/19. |
4675656 | Jun., 1987 | Narcisse | 340/539. |
4747120 | May., 1988 | Foley | 379/38. |
4812823 | Mar., 1989 | Dickerson | 340/572. |
4924211 | May., 1990 | Davies | 340/573. |
5103474 | Apr., 1992 | Stoodley et al. | 379/58. |
5300939 | Apr., 1994 | Meada | 343/703. |
Foreign Patent Documents | |||
51-312865 | Nov., 1993 | JP. |